The major effort during the tenure of this grant will be directed towards a better understanding of DNA replication in procaryotes and eukaryotes. We plan to continue our studies on the different stages of phi X DNA synthesis. A number of proteins involved in these reactions have been isolated and characterized. We will continue in our attempts to define proteins involved in eukaryotic DNA replication. In these studies, we plan to utilize the replication of adenoviral DNA. The processing of RNA will be continued. In particular, the mechanism generating the utilized triphosphates termini on RNA will be examined. The possible role of an RNA ligase in eukaryotic RNA processing will be examined. The processing reactions as well as the mechanism of maintaining 5'-triphosphates on capped ends will be carried out in Vaccinia and in HeLa cell extracts.